An inpatient program with selected overnight stays for childhood and adolescent neuropsychiatric disorders is ongoing. The conditions currently under study are hyperactivity and Gilles de la Tourette's Syndrome. Pharmacological compounds under study in these disorders include methylphenidate, amphetamine, piribedil, Clozapine, and haldol. Pharmacokinetic studies with behavioral correlations are ongoing. Central neurotransmitters and nucleotides and their metabolites are being studied in plasma and urine. Early findings indicate that the amphetamine half-life in children is about 1/3 that of adults. Behavior and motor activity response do not correlate with plasma amphetamine levels. These responses occur during the absorption phase as determined by serial plasma amphetamine following a single dose.